Ground track tracer and landing recorder



4 Sheets-Sheet l E. NORDEN ET AL GROUND TRACK TRACER AND LANDING RECORDER Filed July 15, 1941 INVENTORS ELWOOD NORDEN ARTHUR R.WECKEL THEIR ATTORNEY 1943- E. NORDEN ET AL 2,332,523

GROUND TRACK TRACER AND LANDING RECORDER Filed July 15, 1941 4 Sheets-Sheet 2 MOTOR SELSYN 9 REPEATER I23 lll TROLLEY I39 I49 I LIDE- PATH I09 IOOO MARKER/Y T [O ',+MARKER 3 T RADIO H9 TRANSMITTER l3| OBST UCTIONS RANGE ARKER [4| RAB T ACK IOQ TROLLEY FIG-.5

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AMPLIFIER ALTIMETER MOTOR INVENTORS ELWOOD NORDEN By ARTHUR R.WECKEL M? AM Oct. 26, 9 3- E. NORDEN ETAL GROUND TRACK TRACER AND LANDING RECORDER Filed July 15, 194]. 4 Sheets-Sheet 3 FIG-.E:

ELWOOD NORDEN I I I INVENTORS ARTHUR R WECKEL THEIR ATTORNEY SUPPLY Oct. 26, 1943- E. NORDEN ET AL 2,332,523

' GROUND TRACK TRACER AND LANDING RECORDER Filed July 15, 1941 4 Sheets-Sheet 4 FIG-.7 Lm,

TO CRAB MOTORS INVENTORS ELWOOD NORDEN ARTHUR R.WEC EL T H El R ATT.ORNEY Patented Oct. 26, 1943 UNITED STATES PATENT OFFICE GROUND TRACK TRACER AND LANDING RECORDER Elwood Norden, Pelham, and Arthur B. Weckel, Freeport, N. Y., assignors to Sperry Gyroscope Company, Inc., Brooklyn, N. Y., a corporation of New York Application July 15, 1941, Serial No. 402,464

28 Claims.

In applicants prior copending application Serial No. 309,154, filed Dec. 14, 1939 for Pilot trainer ground track tracer, of which the present ap flication is a continuation-in-part, there is disclosed a ground track recorder for pilot trainers of the link iupe. As is described in the above application, in the pilot trainer of the Link type the trainer heading is transmitted to the recording mechanism or crab to control rection into consideration and will trace a true (simulated) ground track. In the above application, this is done by manually setting in the assumed wind speed and direction into the "crab control mechanism. The device as described in the above application is useful mainly with constant assumed wind conditions, since any change in wind speed or direction during a simulated flight will not be accurately transmitted to the "crab" to correctly compensate the recorded ground track.

The present invention contemplates overcoming the above limitation in the prior application, thereby permitting the assumed wind conditions to be arbitrarily varied during the course of a simulated flight without affecting the trueness of the ground track record traced by the era The present invention further contemplates adapting the device of the prior application, as modified herein, for use on actual aircraft as well u on pilot trainers, so that the pilot of an aircraft can have a complete plot of his actual course and ground speed during flight. The device is also equipped with an indicator which will indicate true ground speed, once the wind speed and direction have been set into the device. Furthermore, should wind conditions change during flight, the pilot can reset the new wind conditions into the device and thereby,

maintain an accurate course plot and ground speed indication. I

v The present invention also includes the addition, to a device of the above character, of a device for recording the landing path of airplanes, adapted for actual aircraft or for pilot trainers of the Link type, whereby the ground plot of a landing approach is made at the same by the airplane. Such a dual recorder is of especial advantage when used in a pilot trainer, since a complete record of a simulated blind landing may be made, giving the student pilot actual training in blind landings, without any of the danger of the actual landing, and permitting him a chance to see his errors without personal danger. It is also of value in the testing of various types of blind landing systems and indicators,

as the practical utility of such systems can be obtained directly from the records made- When used on an actual airplane, a complete record of the landing is made, whereby all details of a landing may be determined and recorded for future use.

It is an object of this invention to provide a course recorder for craft moving in a flowing medium, which will record the true course with respect to the earth, regardless of the effect of said medium on the course of the craft.

It is a further object of the present invention to provide a novel course recorder for aircraft which will record th true ground track, allowing for airspeed and direction, and for wind speed and direction.

It is another object to provide a novel course recorder for a pilot trainer, which will record the simulated ground track of such a trainer, allowing for simulated air speed and direction, and

an assumed wind speed and direction.

It is a further object to provide a novel course recorder for aircraft or pilot trainers which will plot a true ground track despite arbitrary variations of wind speed or direction, or of air speed or direction.

in wind speed and direction may be manually adjusted for, while maintaining an accurate ground track record.

It is still another object of this invention to provide a simulated ground track recorder for pilot trainers which will automatically allow for variations in simulated air speed and craft heading, and in which variable assumed wind conditions may be set into the recorder mechanism while maintaining an accurate record of the simulated ground track.

It is a further object of thisinvention to provide a ground track recorder for aircraft or pilot trainers which will automatically allow for variatime as the plot of the actual glide path assumed tions in air speed and craft heading, and in which the wind speed and direction may be manually set and varied as wind conditions change.

It is a further object of this invention to pro-v vide a novel true ground speed indicator for aircraft.

It is a still furtherobject of this invention to provide a ground speed indicator for aircraft which will automatically allow for varying air speed conditions, and in which changes in wind speed may be manually compensated for, to yield an indication of true ground speed.

It is another object of this invention to provide a novel landing recorder for aircraft or for pilot trainers of the Link type.

It is still another object of this invention to provide a combined landing and ground track recorder whereby a complete record both in plan and elevation, may be made of an aircraft landing, or a simulated landing in a pilot trainer of the "Link type.

It is a further object of this invention to provide a landing recorder for aircraft or pilot trainers which is actuated by the altimeter of said craft or trainer to give an accurate calibrated record of the glide path of the craft or simulated glide path of the trainer.

Other objects and advantages will become apparent from the specification, taken in connection with the accompanying drawings wherein one embodiment of the invention is illustrated.

In the drawings,

Fig. 1 shows an elevation, partly in section, of the triangulation device and associated apparatus used in the course recorder of the present invention.

Fig. 2 shows a plan view of the combined course and landing recorder of the invention.

Fig. 3 shows a detail partly in section of the device of Fig. 2, taken along the line 3-3 of Fig. 2.

Fig. 4 shows a remote position-controlling system suitable for use with the devices of Fig. 1 r Fig. 2.

Fig. 5 shows a cross-section of the device of Fig. 1 taken along lines 55.

Fig. 6 shows a control circuit for controlling the speed of the recording crab in accordance with true ground speed.

Fig. '7 is a wiring diagram of an air speed con trol circuit.

Fig. 8 shows the wiring diagram of a modification of the circuit of Fig. 6.

Figs. 9 and 10 are elevations of a clock-operated inking mechanism for speed indication recording; and

Fig. 11 shows the wiring diagram for the differential synchro-transmitter.

Similar characters of reference are used in all of the above figures to indicate corresponding parts.

Figs. 1 and 5 show the triangulation device or the invention. These figures are the same as Figs. 1 and 6 of applicants above-mentioned prior application, except for the addition of annular gear ll. pinion l3 and differential synchro-transmitter l5, whose uses will be explained below The detailed operation of the device, except as modified by the added elements. will not be repeated here since it is already given in the prior application. The general operation, when applied to a pilot trainer, is as follows:

The azimuthal motion of the trainer is transmitted to shaft l1 and is thence transmitted through suitable gearing, etc., described in the prior application, to orient arm IS in accordance with the heading of the trainer. This determines the direction of the air speed vector in the triangulation problem to be solved. The simulated air speed of the trainer is transmitted by a suitable mechanisrn, shown in Fig. 7, to actuate screw 2| and thereby determine the length of the air speed vector. The trainer air speed meter feed line or pressure tub 6 is connected to a bellows 8, the right-hand end of which is movable according to air pressure therein and which actuates arm [0 of potentiometer l2 as the air speed, and hence the pressure in line 6, varies. It will be understood that the air speed meter (not shown) is of a conventional form creating an air pressure in the tube or line 6 proportional to the speed of the aircraft relative to the air in which it flies. Screw 2| carries a nut 22 holding the slider ll of repeat-back potentiometer I8. The voltage corresponding to the difference in setting of the arms Ill and I4 actuates motor 24 by means of amplifier 20. A feed back generator 26 is used to prevent hunting. In this way, nut 22 is continuously positioned in accordance with the position of arm I 0, which in turn corresponds to the air speed, since the amount of distension of the bellows 8 depends on the pressure in th line 6 which varies with air speed.

The assumed wind direction is set into the mechanism of Fig. 1 by rotating bracket 23 connected to table 25 through the proper angle, until bracket 23 is oriented in the directim of the assumed wind as determined by a suitable index on table 25 cooperating with a suitable scale 26 on fixed housing 21. The assumed wind speed is set in by turning screw 29, which effects relative displacement between shafts 3| and 33 as seen best in Fig. 5. In this manner, the two vectors representing air velocity and wind velocity are set into the device, and their resultant will be the simulated ground speed both in magnitude and direction. The simulated ground speed direction is transmitted to a remote point by synchrotransmitter 35. Transmitter 35 actually transmits the angle between the simulated ground speed and assumed wind speed vectors. To indicate actual simulated ground speed direction with respect to a fixed datum direction, the output of transmitter 35 is fed into the differential synchrotransmitter l5 fastened as by a bracket I6 to housing 21, whose rotor is turned by annular gear H through pinion l3, Annular gear II is fastened to bracket 23 and table 25. The tooth ratio of gears II and I3 is made the same as that between pinion 38 on transmitter 35 and its driving gear 39, so that differential transmitter I5 compensates for the assumed wind direction, and

its output, when fed to a remot xindicator, will indicate true (simulated) ground speed direction whose correctness is unaffected by changes in assumed wind conditions.

Fig. 11 shows the wiring diagram for this differential synchro-transmitter l5. This transmitter has two polyphase-type windings 34, 36, one being fixed to the casing and the other one being fixed to the rotor. The output of synchro-transmitter 35 is connected directly to one of these windings, illustrated here as being the stator winding 34. Then the output of the other, or rotor, winding 36 is connected to synchro-receiver, or repeater motor, 15 which orients the wheels of the crab, as will be seen in Fig. 6.

The true ground speed is transmitted to the recording crab, to control the speed of the crab, as a varying frequency which is controlled by rotation of a two-section rheostat 55-51 (see Figs. 6 and 8) contained with a casing 39 (shown in Fig. l) which rheostat is the frequency-determining element in an oscillator circuit, as described below.

Fig. 6 shows a suitable control circuit for the recorder. Tube 43 and its associated circuit elements form a fixed frequency oscillator of the conventional feed-back type, the frequency being determined by tuned circuit 45 and the energy being fed back from plate to grid by resistor 41 and condenser 49. Resistance coupled tubes and 53 form a two stage resistance-condenser oscillator in which part of the output of tube 53 is fed back to the input of tube 5| by means of variable rheostat sections 55 and '51 and condensers 59, 5|. Such a circuit will oscillate only at the frequency at which the phase of the feed back voltage is proper to sustain oscillation. Accordingly the frequency may be varied by varying the rheostat sections or members 55, 51. This tends to change the phase of the feed back voltage, and the frequency shifts to maintain the proper phase relation. As shown, the members or rheostats 55, 51 may be ganged and controlled by bevel gear 4|, as indicated at 39, Fig. 1. Since the variation of frequency of the resistance-capacitance oscillator is not linear with respect to rotation of rheostats 55, 51, if the rheostat resistances vary linearly with rotation thereof, suitable means are provided for correcting for such non-linearity in the frequency-resistance relationship of the oscillator. For example, cams (not shown) may be introduced between gear 4| and the rheostats to compensate for any non-linearity, so that the .output frequency will bear a linear relationship to rotation of shaft 3|. .I-f cams are employed, they are provided with an empirically derived contour. The proper contour is most conveniently determined by plotting the variation in frequency against the rheostat rotation and so shaping the cam, in a manner well understood to those skilled in the art, that each uniform increment of rotation of the gear 4| produces such a non-uniform increment of rotation of the rheostats 55 and 51 as to make the frequency change linear.

The outputs of variable frequency oscillator 5|53 and of constant frequency oscillator 43 are mixed in mixer stage 53 and the difference or beat frequency is selected by tuned circuit 65. This difference frequency is amplified in amplifier stage 61 and then sent to the remotely situated recording crab 59 over lines 1|. The difference frequency voltage is applied to synchronous drive motors 13 to drive the crab-at a speed proportional to the input frequency and hence proportional to the rotational position of shaft 3|. Of course, the variable frequency oscillator is adjusted to give zero beat with fixed frequency oscillator 43 for zero ground speed.

The orientation of crab 69 is controlled by Selsyn repeater motor 15, energized from Selsyn transmitter |5 as described above.

The use of beating oscillator 43 and mixer 63 is not always necessary. The resistance capacitance oscillator 5|, 53 may be adjusted to give a wide range frequency output, starting at a very low frequency. Accordingly, this oscillator may drive the crab directly. Such a control circuit is shown in Fig. 8, where tubes 5|, 53 vform an oscillator of the type described above, whose frequency is controlled by two-section rheostat 55, 51. A voltage regulating lamp 52 is used to stabilize, and to improve the wave shape of, the oscillator output. Amplifier stages 66 and 51 amplify the oscillator voltage to a value suitable for control of the repeater-motor 15.

Fig. 8 also contains a calibrating device. The frequency of the output voltage across line 1| is compared with that of the alternating current source by means of neon lamp 10. Variable arms of rheostat section 55, 51 are adjusted, relative to their driving. shaft, so that at a predetermined speed, which may correspond to normal cruising speed of the pilot trainer, the frequency of the oscillator will be substantially equal to that of the alternating current source, as determined by lack of, or at least very slow, blinking of neon lamp 1..

Since rotation of shaft 3|, and hence of pinion 4|, is responsive to the true ground speed, it is merely necessary to provide a properly calibrated scale 44 and index 46 (Fig. 1) to indicate true ground speed. Alternatively, a properly calibrated frequency meter 11 may be connected to the input of the crab driving motors (Fig. 6) and may thereby indicate true ground speed by its reading.

The above description was concerned with the use of our device with a pilot trainer. It is also applicable to use on actual airplanes. For such use, the shaft |1 must be actuated by the direction indicator such as the compass or directional gyro of the airplane to automatically respond to changes in the craft heading. This can easily be done by well known remote positioning devices. A suitable device is shown in Fig. 4, being there applied to remote positioning of a shaft 1 in accordance with the position of an altimeter H9, as described below, but could as readily be adapted to control the position of shaft H in accordance with the position of a conventional direction indicator.

Also, screw 2| must be actuated by the air speed indicator to automatically allow for craft air l0 (Fig. '1) in accordance with the air speed indications, by well known means, similar to Fig. 4 of the present application.

The wind velocity and direction may be adjusted by the pilot in accordance with weather reports he may receive by his radio apparatus. The wind conditions may be readjusted in accordance with each weather report, without affecting the correctness of the record made by the recording cra Where used with an airplane, the crab may be placed anywhere on the craft, as it requires only seven wires for its complete energization: two for its speed control, and five for the direction indication by its synchro-receiver 15. If desired, the currents in these seven wires may be sent by radio to a ground station as by modulating five separate carriers or sub-carriers, three carriers being modulated with the three rotor currents output from rotor winding 36 of a differential synchro-transmitter I5, one with theenergizing current for synchro-receiver 15, and one with the output of amplifier 51 (Figs. 6 or 8) for speed control. The ground station can thereby keep an accurate record of the path of the craft. This would be very useful in dispatching traffic over an entire system, and in finding lcst planes, as the record of the path of such planes will be available at the ground station.

It is clear that the device explained above is not limited to use with aircraft. It may be readily applied to any craft moving in a flowing medium, as, for example, boats, and also to any problem where velocity relative to a moving reference system (air, water, earth, etc.) is to be translated over into velocity relative to another reference system.

Fig. 2 shows the recording equipment for plot ting a complete record of an aircraft landing. A chart IOI shows a plan view of the field and its surroundings on the lower part. The upper part of chart IOI shows an elevation of the landing path.

The "crab I03, which is actuated as described above and in our above mentioned prior application, carries two guide bearings I05, in which is inserted a guide rod I01. This rod I01 is kept from longitudinal movement by trolleys I09 which ride on tracks III. This arrangement will not interfere with the ordinary motion of the crab since the body of the crab does not change orientation, only the wheels turning to change the direction of travel.

Also guided by rod I01 is a recording pen II3, whose carrier H is supported by guide bearings I05 from rod I01 so as to be able to slide along rod I01. The pen H3 is moved by drive screw II1, which rotates in drive nut II9 fastened to pen carrier I I5.

Drive screw H1 is actuated remotely by the craft or trainer altimeter. An illustrative method is shown in Fig. 4, where an altimeter, illustrated schematically at I I9, is shown coupled to synchrotransmitter I2I. This actuates synchro-receiver I23, generating a voltage in rotor I25 of the receiver in response to rotation of the transmitter rotor I22. This voltage is amplified in amplifier I 21, which may, and preferably does, include any known type of anti-hunt circuit, and is then used to actuate motor I29. Motor I29 turns screw I I1, and at the same time turns receiver rotor I25. when rotor I25 has been turned to a position corresponding to the position of the transmitter rotor, the voltage generated in rotor I25 becomes zero, and the motor I29 stops. The anti-hunt circuits insure dead-beat operation. Thus, the pen II3 continuously assumes a position corresponding to the position of the altitude indicator of the craft or trainer. The motor I29 and/or receiver I23 may include speed changing mechanism to provide for any ratio of motion between the altimeter H9 and pen II3.

Thus, it is seen that this device will give a continuous indication of the actual motion of the aircraft or the simulated motion of a pilot trainer, both in plan and in elevation. For convenience, chart IOI may have indicated thereon the radio range I 3|, the localizer beacon I33, the marker beacons I35, I31, the glide path I39, the radio transmitter location III and the runways I43, as well as field obstacles I43. The resulting record of a typical flight or test will be similar to trace I45.

Rod I01 and chart IOI ma be calibrated directly in feet of altitude, as shown at I41, I 49, so that the recorder can also act directly as a remote altitude indicator.

Since the recording mechanism I03 and I I 5 need be connected to the main body of the craft only electrically, remote indication and recording can be very conveniently practiced. If desired, the proper signal currents could be transmitted by radio from the airplane to a landing field to actuate a recorder at the field.

The plot of the landing will necessarily have to be to a scale much larger than that used during ordinary course plotting. This will necessitate some type of speed changing mechanism for crab" I03. One way of avoiding the use of speed changing devices is to use two "crabs having different gear ratios. One would have the ratio necessary to cooperate with the rather small scale of a course plot, while the other would have a ratio suitable for use with the landing chart. Electrical switching-over from one crab" to the other may be done manually, at some convenient point, such as when passing over marker beacon I35. If two crabs are employed, there may be two charts with associated recording equipment such as illustrated in Fig. 2, one with a large scale for recording landings and the other with a small scale for recording course and altitude during flight. Changing the triangulation device of Fig. 1 and the altimeter 9 (Fig. 4) from one recorder to the other involves merely changing the electrical connections from one recorder to the other by a simple multipole double throwswitch which need not be illustrated. It will be understood that the connections to be transferred comprise the speed signal carrying conductors N (Fig. 6), the azimuth signal carryin conductors between the windings 36 and 15 (Fig. 11) and the altitude signal carrying conductors between the windings I2I and I23 (Fig.4).

As a further means of indicating and also recording ground speed, the crab I03 may carry a clock and pen mechanism, such as shown in Figs. 9 and 10, which will operate to periodically place a dot beside the course record, as seen at I30 in Fig. 2. Since these dots will be placed at equal intervals of time, their spacing will give an indication of ground speed. A series of closely spaced dots will indicate a fairly slow speed, while a series of widely spaced dots will indicate high speed. By knowing the actual time interval between dots, the ground speed can be found by measuring the actual distance between dots, on the chart and computing the speed.

Referring to Figs. 9 and 10, reference character 8| represents the inking wheel of the crab, supported from a stanchion 83. A clock mechanism of any suitable type is also supported from support 83, and is mechanically connected, as by reduction gearing 01, to cam 9I, which is thereby caused to rotate at a fixed rate, such as one revolution per minute. Also mounted on supporting leg 83, as by a bracket or boss 93, is an inking member 95, normally held away from engagement with chart IN by spring 91. However, upon rotation of the cam 9|, its high spot 99 will depress the inker 95 and cause it to leave an ink spot or dot on chart IOI. Inker 95 is ,fed from an ink reservoir as by a flexible tube 92. Thus inker will periodically leave a dot beside the trace left by inking wheel 8|, whereby the speed along the trace may be determined.

As many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A course recorded for craft moving in a flowing medium comprising a triangulation device having three variable arms, means for continuously adjusting one arm of said device to correspond to the heading and speed of said craft through said medium; means for continuously adjusting a second arm of said device to correspond to the speed and direction of said medium with respect to the earth, a recording element, means operating in response angular orientation of said third arm for controlling the direction of motion of said element. whereby said element will trace the true course of said craft with respect to'the earth in response to motion of said craft.

2. A course recorded for craft moving in a flowing medium comprising a triangulation device having three arms variable in length and orientation, means for continuously adjusting one arm of said device to correspond to the heading and speed of said craft through said medium, means for continuously adjusting a second arm of said device to correspond to the speed and direction of said medium with respect to the earth, a recording element, means operating in response to the length of thethird arm of said device for controlling the"spe'qd of said recording element, and means operating in response to the angular orientation of said third arm for controlling the direction of motion of said element, whereby said element will trace the true course of said craft with respect to the earth in response to motion of said craft.

3. A course recorder for aircraft comprising a triangulation device having three variable arms means for adjusting one arm of said device to correspond to the airspeed and heading of said craft, means for adjusting a second arm of said device to correspond to the wind direction and speed, a movable recording element, means operating in response to the length of the third arm of said device for controlling the speed of motion of said recording element and means operating in response to the angular orientation of said third arm for controlling the direction of motion'of said element.

4. A course recorder for aircraft comprising a triangulation device having three arms variable in length and orientation, means for adjusting one arm of said device to correspond to the airspeed and heading of said craft, means for adjusting a second arm of said device to correspond to the wind direction and speed, a movable recording element, means operating in response to the length of the third arm of said device for controlling the speed of motion of said recording element and means operating in response to the angular orientation of said third arm for controlling the direction of motion of said element.

5. A course recorder for craft moving in a flowing medium, comprising an automatic triangulation device having two variable arms adjustable in orientation and length, and also having a resultant arm whose length and orientation determine a vector which is the resultant of the two vectors formed by the orientation and length of each of the two variable arms, means for orienting one of said variable arms in a direction corresponding to the heading of said craft with respect to the earth, means for adjusting the length of said one variable arm in accordance with the speed of said craft through its surrounding medium, means for orienting the second of said variable arms in a direction corresponding to the direction of motion of said medium with respect to the earth, and means for adjusting the length of said second arm in accordance with the speed of said medium with respect to the earth, a recording device, means for controlling the speed of motion of said recording device in accordance with the length of said resultant arm and means for controlling the direction of motion of said recording device in accordance with the orientation of said resultant arm, whereby said recording device traces a path representing theatrue course of said craft with respect to the earth.

6. A course recorder as in claim 5 in which said means for controlling the speed of said recording device comprises means for positioning a shaft in accordance with the length of said third arm, means for generating electrical oscillations, means controllable by the position of said shaft for varying the frequency of said oscillations, and means for moving said recording device at a speed proportional to said frequency. 7. A course recorder as in claim 5, in which the means for controlling the direction of motion of said recording device includes means for generating electrical signals corresponding tn the orientation of said third arm with respect to said second arm, means for transforming said signals to correspond to the orientation of said third arm with respect to said craft, and means for orienting said recording device under control of said transformed signals.

8. In a recorder system for aircraft, a ground track tracer having wheels adapted to move over a chart or map, motive means for driving said wheels to trace said ground track, additional motive means for orienting said wheels, a triangulation device,'means for supplying said device with data corresponding to the air speed and heading of said craft, means for supplying said device with further data corresponding to wind speed and direction, means controlled from said triangulation device for operating said first motive means in accordance with the resulting ground speed of said craft, and additional means controlled from said triangulation device for operating said additional motive means for orienting said wheels in accordance with the ground course of said craft.

9. A course recorder for aircraft comprising a recording element, motive means for driving said recording element to generate a trace, additional motive means for orienting said recording element, a triangulation device, means for supplying said triangulation device with-data corresponding to the airspeed and heading of said craft, means for supplying said triangulation device with data corresponding to wind speed and direction, means controlled from said triangulation device for operating said first motive means in accordance with the resulting ground speed of said craft and means controlled from said triangulation device for operating said additional motive means for orienting said element in accordance with the ground course of said craft.

10. A course recorder for a craft moving in a flowing medium comprising a course indicator having a recording element, means for moving said element with respect to a reference surface at a speed corresponding to the speed of said craft with respect to said medium and in a direction corresponding to the heading of said craft, and means for simultaneously altering the relative movement between said element and said surface in a direction and at a speed corresponding to the direction and speed of said medium with respect to the earth.

11. A course recorder for aircraft comprising a recording element, means under the control of conditions representing the heading and airspeed of said craft for moving said element with respect to a reference surface, and means for simultaneously altering the relative movement between said element and said surface in a direction and at a speed correspondnig to the wind direction and speed.

12. A course recorder for craft moving through a flowing medium comprising a recording element, means under control of conditions representing the heading and speed of said craft with respect to its surrounding medium for moving said element with respect to a reference surface, and means for simultaneously altering the relative movement between said element and said surface in a direction and at a speed corresponding to the direction and speed of said medium with respect to the earth. i

13. In a recorder system for aircraft, a ground track tracer having wheels adapted to move over a chart or map, motive means for driving said wheels to trace a track on said chart, additional motive means for orienting said wheels, means for controlling said first motive means in respons to the airspeed of said craft, means for controlling said additional motive means in response to the heading of said craft, and means for compensating both of said motive means for wind speed and direction whereby said tracer traces the actual ground track of said craft.

14. In a recorder system for aircraft, a ground track tracer adapted to move over a chart or map, motive means for driving said tracer to trace a track on said chart, additional motive means for orienting said tracer, means for controlling said first motive means in response to the airspeed of said craft, means for controlling said additional motive means in response to the heading of said craft, and means for compensating both of said motive means for wind speed and direction, whereby said tracer traces the actual ground track of said craft.

15. In a recorder system for aircraft, a ground track tracer having wheelsadapted to move over a chart or map, motive means for driving said wheels to trace said ground track on said chart and additional motive means for orienting said wheels, means for controlling said first motive means in response to the ground speed of said craft, means for controlling said additional motive means in response to the ground course of said craft, a glide path recording element adapted to move over a separate portion of said chart, means for connecting said element to said tracer for motion in one direction with respect to said chart and means for moving said element in another direction with respect to said chart under control of the altitude of said craft.

16. In a recorder system for pilot trainers, a ground track tracer having wheels adapted to move over a chart or map, motive means for driving said wheels to trace said track on said chart and additional motive means for orienting said wheels, means for controlling said first motive means in response to the simulated ground speed of said trainer, means for controlling said additional motive means in response to the simulated ground course of said trainer, a glide path.

recording element adapted to move over a separate portion of said chart, means for connecting said element to said tracer for motion in one direction with respect to said chart and means for moving said element in another direction with respect to said chart under control of the simulated altitude of said trainer.

17. A recorder system for aircraft or pilot trainers comprising a ground track tracer having wheels adapted to move over a chart, motive means for driving said wheels under control of conditions representing ground speed to trace said ground track on said chart, additional motive means for orienting said wheels under control of conditions representing ground course bearing, a recording element adapted to move over a separate portion of said chart, means for connecting said element to said tracer for motion in one direction with respect to said chart, and means for moving said element in another direction with respect to said chart'under control of conditions representing altitude.

18. A combined course and landing path recorder for aircraft, comprising a. first recording element, means for moving said element with respect to a reference plane in a direction and at a rate corresponding to the ground track and ground speed of said craft, a second recording element, means connecting said elements to transmit motion of said first element in a predetermined direction to said second element and means for moving said second element perpendicular to said direction in accordance with the altitude of said craft.

19. A combined course and landing path recorder for aircraft or pilot trainers, comprising a ground track recording element, means for moving said element with respect to a reference surface in a direction and at a rate under control of conditions representing ground course and ground speed, a landing path recording element, means connecting said elements to transmit motion of said ground track recording element in one direction to said landing path recording element and means for moving said landing path recording element perpendicular to said one direction under control of conditions representing altitude.

20. A dual recorder comprising a first recording element, a chart, means for moving said first element over said chart in response to remote conditions to trace a desired record, a second recording element, means connecting said elements for moving said second element over a separate portion of said chart in a single direction under control of said first element, and means for moving said second element in another direction under control of conditions independent of said first element.

21. A landing path recorder for aircraft comprising a recording element, means for moving said element in one direction in accordance with forward horizontal motion of said craft and means for moving said element in another direction in accordance with the altitude of said craft.

22. A landing path recorder for aircraft or pilot trainers comprising a recording element, a chart, means for moving said element over said chart under control of conditions representing forward horizontal motion and means for moving said element in another direction under control of conditions representing altitude.

23. A recorder as in claim 1 in which said means for controlling speed of the recording element includes, an adjustable frequency source of electrical oscillations, means for adjusting said frequency in response to the length of said third arm, synchronous motor driving means for said element, and means energizing said motor by electrical oscillations of said adjusted frequency, and which further comprises frequency measuring means connected to said source of adjusted frequency oscillations for indicating true speed of said craft with respect to the earth.

2'4. A course recorder as in claim 3 in which said means for controlling the recording element speed includes a variable frequency oscillator having a positionable frequency-determining device, means for positioning said device under control of the length oi. said third arm, motive means for said recording element, and means for controlling the speed of said motive means in response to the frequency output of said oscillator, said course recorder further comprising frequency-measuring means connected to said oscillator for indicating the ground speed of said craft.

25. A course recorder a in claim 12, further including a second recording element carried with said first element and means for periodically actuating said second element to place a mark at equal time intervals beside the trace left by said first recording element. whereby the speed of said craft may be determined as a function of the relative spacing of said marks.

26. A ground speed indicator for aircraft comprising a variable frequency oscillator having a positionable frequency determining element, means for positioning said element in accordance with the air speed of said craft, means for simultaneously altering the position of said element in accordance with wind conditions and means for indicating the frequency of the wave generated by said oscillator.

27. A speed indicator for craft moving through a flowing medium comprising a variable-frequency-oscillator having a positionable frequency-determining element, means for positioning said element under control of conditions representing speed of said craft with respect to its surrounding medium, means for simultaneously altering the position of said element under control of conditions representing speed and direction of flow of said medium with respect to the earth, and means for indicating the frequency of the wave generated by said oscillator thereby indicating the speed of said craft relative to the earth.

28. A device for controlling the speed of an object in accordance with the angular position of a shaft, comprising means for generating electrical oscillations, means for controlling the frequency of said oscillations by the position of said shaft, synchronous motor motive means for moving said object, and means for controlling said motive means by said oscillations.

ELWOOD NORDEN. ARTHUR R. WECKEL.

Disclaimer 2,332,523.-Elw0od Norden, Pelham, and Arthur R. Weckel, Freeport, N Y. GROUND TRACK TRACER AND LANDING RECORDER. Patent dated Oct. 26, 1943. Disclaimer filed'Mar. 18, 1948, by the assignee, The Sperry Uorporat'ion.

Hereby enters this disclaimer to claims 8, 9, 10, 11, 12, 13, and 14 of said patent,

(Oflicial Gazette April 20, 1948.)

Disclaimer 2,332,523.Elw00d Norden, Pelham, and Arthur R. Weckel, Freeport, N Y. GROUND TRACK TRACER AND LANDING RECORDER. Patent dated Oct. 26, 1943. Disclaimer filed'Mal 18, 1948, by the assignee, The Sperry Corporation.

Hereby enters this disclaimer to claims 8, 9, 10, 11, 12, 13, and 14 of said patent,

0 7ml Gazette April 20, 19 8. 

